RU2797867C1 - Diamond detector-based diamond detector recognition system for fluxes of corpuscular radiation for laser fusion time-of-flight spectrometry - Google Patents

Abstract

FIELD: radiation measurement.

SUBSTANCE: invention relates to the field of measurements of neutron, x-ray, corpuscular, gamma radiation. The corpuscular radiation flux registration system consists of a diamond detector, which is connected to high-resolution recording equipment, which includes a high-frequency preamplifier, an electronic module for converting and reproducing diamond detector signals, and a high-speed ADC. The diamond detector is a coaxial housing in which a diamond sensitive element is placed, which is a thin high-purity diamond single-crystal layer about 20 μm thick, grown by CVD on a diamond HPHT substrate with a boron content of at least 100 ppm, and in which on the back side of the diamond substrate and metal contacts are deposited on the CVD diamond layer.

EFFECT: measurement of the spectra of products of thermonuclear reactions, namely: protons, tritons, He³, He⁴, gamma radiation, as well as 2.5 and 14 MeV neutrons, increasing the radiation resistance of the detector, which has a collapsible design and small dimensions.

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Description

Description of the invention

The invention relates to the field of measuring neutron, x-ray, corpuscular, gamma radiation with a semiconductor detector, namely a diamond detector.

The corpuscular radiation flux detection system based on a diamond detector is intended for use in laser thermonuclear fusion.

Most registration systems for pulsed neutron, corpuscular fluxes are built on the basis of detectors in which various scintillators are used as sensitive elements (patent CN 111796320 A, publ. 10/20/2020; S. Cierjacks, T. Petkovic et. Al. Nuclear Instruments and Methods in Physics Research, V. A238, p. 354-364, 1985). These detectors are not capable of distinguishing between different types of radiation. In addition, scintillation detectors often require cooling to optimize their sensitivity, as their performance decreases with increasing temperature.

Known time-of-flight pulsed neutron detector (patent US 2014/0077093 A1), containing a GEM detector (gas-electron multiplier), including a drift electrode coated with a layer of neutron-converting material to generate an electric field, a lot of GEM-boards coated with a layer of neutron-converting material, a time-of-flight reading unit for detecting the 2-D position of an electron, a timer electronic circuit for fixing the time of flight of a pulsed neutron using independent arbitrary tuning, and a microprocessor unit for performing a digital calculation of the time of flight.

The use of traditional semiconductor detectors with a band gap of 1–2 eV for measurements is problematic due to unstable operation and low radiation resistance. Known time-of-flight detection system for neutron radiation at the NIF (National Ignition Facility) USA, which uses 3 neutron detectors based on polycrystalline diamond of different sensitivity (69. Yu, V., Glebov et al. “The National Ignition Facility neutron time-of- flight system and its initial performance)). Rev. sci. Instrum. V. 81.10D325.2010).

The closest analogue (prototype) of the invention is a device for detecting neutrons with a detector having a pair of spaced diamond detector layers sandwiched between outer layers of silicon (patent US 2018/0120460 dated 03.05.2018 "Neutron imager with spaced diamond detector arrays"). In response to incident neutrons, the detector system measures the pulse height and response time, and from these measurements calculates the carbon recoil energy and the time of flight of the scattered neutrons. The scheme of the device includes a diamond detector, various measuring and technological equipment, and an imager. The detector is a "two-stage" detector having a diamond detector layer and an associated thin layer of silicon. Each diamond detector layer is a set of single-crystal diamond detectors (three by three matrix, consisting of nine crystals, 7×7×0.5 mm in size). In this example, 5×5×0.5 mm diamond plates are used. The layers of the diamond detector and silicon form a "sandwich", while the silicon layers are located on the outer sides of the detector and serve to cut off the background. Two blocks of diamond detectors are inside. The signal from the detector is fed to a preamplifier, amplifier, and analyzer, such as the Clearpulse 580K, Ortec 572A, and Amptek MCA800A, respectively. Time of flight (TOF) measurements use time delay signals between a pair of detectors. The detector output of the first detector is fed into the response time measurement circuit (here it contains fast charge amplifiers and constant fraction discriminators (CFDs)). This response time is a measure of the speed of the pulses, which makes TOF measurements possible.

This detection system is suitable for low energy neutron measurements in the range of 10 keV to 1 MeV and has a complex structure of the detecting element.

The purpose of the present invention is to provide measurements of the spectra of products of thermonuclear reactions, namely: protons, tritons, He ³ , He ⁴ , as well as 2.5 and 14 MeV neutrons, on the basis of which it is possible to analyze the structure of the LTS thermonuclear source, with one instrument.

This goal is achieved by the fact that the registration system includes a detector based on a diamond single-crystal CVD (chemical vapor deposition) film and high-resolution recording equipment, which includes a high-frequency preamplifier, an electronic module for converting and reproducing diamond detector signals, and a high-speed ADC. The diamond detector makes it possible to register mixed radiation fluxes: X-rays, neutrons, charged products of thermonuclear reactions and analyze the dynamics and spatial distribution of pulsed radiation sources by time delays. This will make it possible to measure the spectra of the products of thermonuclear reactions, namely: protons, tritons, He ³ , He ⁴ , 2.5 MeV and 14 MeV neutrons, gamma radiation, on the basis of which it is possible to analyze the structure of the LTS thermonuclear source. The diamond detector will measure the time of flight of neutrons and alpha particles emitted by the target. The time of arrival at the detector carries information about the energy of the registered particles, and the spread of arrival times will make it possible to measure their temperature.

The sensitive element of the diamond detector (figure 1) is a diamond single-crystal CVD film (figure 1, item 1) of high purity with a thickness of about 20 μm, grown on a diamond HPNT substrate (figure 1, item 2) with a boron content of at least 100 ppm On HPHT substrate and CVD film were deposited by magnetron sputtering solid metal contacts (figure 1, pos.3, 4) with a thickness of not more than 35 nm. The contact material can be carbide-forming metals. As a sensitive element, a thin (no more than 100 microns) single-crystal diamond plate of electronic quality with deposited solid metal contacts can be used.

The detector housing is a collapsible structure on a coaxial connector, which is mounted electrode (figure 2, pos.12), a table (figure 2, pos.7), on which the side of the substrate is placed sensitive diamond element (figure 2, pos. 13), fixed by a stopper (figure 2, pos.6), having a hole with a diameter of at least 1.5 mm. The clamp is carried out by a union nut (figure 2, pos.5). As insulators used details of PTFE (figure 2, pos.8, 9, 11).

The design of the detector is collapsible. A significant advantage is the ease of manufacture of the detector housing, quick assembly, which at the same time provides reliable electrical contact. This design allows you to quickly replace the sensing element, if necessary, without replacing the housing parts and dismantling the entire registration system. The device of the diamond detector is shown in figure 2, where 5 is a union nut, 6 is a stopper, 7 is a table, 8 is a nut, 9 is a sleeve, 10 is a detector housing, 11 is a sleeve, 12 is an electrode, 13 is a diamond sensitive element.

Compared with the prototype, the proposed design allows for direct spectrometric measurements of neutrons in the energy range from 2.5 to 15 MeV, as well as protons, tritons, He ³ , He ⁴ and gamma radiation.

Figure 3 shows a diagram of a system for detecting corpuscular radiation fluxes based on a diamond detector for time-of-flight spectrometry of laser fusion, where 14 is a diamond detector, 15 is a high-frequency preamplifier, 6 is an electronic module for converting and reproducing diamond detector signals, 17 is a high-speed ADC.

Claims (1)

A system for detecting corpuscular radiation fluxes, consisting of a diamond detector and recording equipment, including a high-frequency preamplifier, an electronic module for converting and reproducing diamond detector signals, and a high-speed ADC, where the diamond detector has a collapsible design on a coaxial connector, into which an electrode, a contact, and a table on which a sensitive diamond element is placed, which is a thin, about 20 μm thick, high-purity single-crystal diamond layer grown by the CVD method on a diamond HPHT substrate with a boron content of at least 100 ppm, and coated with solid metal contacts as on the side of the diamond CVD layer , and on the back side of the substrate with a thickness of no more than 35 nm.

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